Method of burning cement-making materials



UNITED STATES PATENT FFICE.

JAMES M. WVILLCOX, OF PHILADELPHIA, PENNSYLVANIA.

METHOD OF BURNING CEMENT-MAKING MATERIALS.

SPECIFICATION forming part of Letters Patent No. 420,371, dated January28, 1890.

Application filed June 4:, 1889. fierial No. 313,070. (No specimens) Toall whom it may concern.-

Be it known that I, J AMES M. WILLOOX, of Philadelphia, in the State ofPennsylvania, have invented a new and useful Improvement in the Methodof Burning Cement-Making Materials, of which the following is aspecification.

Myinvention is for the purpose of improving the burning of cement-makingmaterials in a kiln or chamber, and thereby the quality of the cementproduced; and the objects to be more immediately effected for that pur-.pose are to ignite the fuel rapidly, to burn quickly, to distribute theintense heat evenly and thoroughly, to compensate for any deficiency ofheat due to the use of ordinary fuels or any other cause, and toregulate the heat of the kiln uniformly. All these objects are effectedmuch more perfectly by means of my invention than by the ordinary methodof burning in hydraulic-cement kilns; and my invention may be stated ina general way to consist in the employment in the buriiing ofcement-making materials, in conjunc tion with the coal or cokeordinarily associated with such materials in a kiln or chamber, offlaming gas or spray as a carrier of fire, or burner ancillary orauxiliary to the ordinary denser fuel. Any highlycombustible gas willanswer my purpose, if forced in a burning stream into the content-s ofthe kiln; but

I prefer a current of burning oily or tarry or similar spray, for thereasons .that it is not so quickly spent, nor its heat so narrowlylocalized, and I do not claim the use of either except as an auxiliaryor ancillary burner. In practical use I prefer Parsons steam-blower andParsons tar-burner, patented February 6, 1877, and June 15, 1877, as thebest known apparatus for injecting the burning spray or gas.

In illustration of the Value of my invention I instance the manufactureof the Port land or highest grade of hydraulic cement according to thebest method in present use. The cement making materials are apportionedand reduced to powder in a crude or semi-crude state, mixed with acombustible binder of tar, pitch, or other resinous substance, thenpressed or molded into lumps or blocks, and finally laid in the kiln instrata between alternate layers of coal or coke.

The kiln, when thus charged, is lighted at the bottom and the firestruggles through the compact mass, slowly reducing it layer after layerto a condition which fits it for grinding into finished cement. In thisoperation, as the fire slowly ascends, the resinous binder of the layersapproached by it softens, volatilizes, and mostly goes off in vaporbefore the living fire reaches it to ignite it and burn it "in sit u asfuel. This. is a very material loss of the most valuable of all fuels,sincethe binder'is so distributed as to be in contact with everymolecule of the material, and its burning in situ produces a clinker inwhich the elementary cement constituents form the most perfect union.This burning in situ I efifect by my process, and so improve the qualityof the cement as well as quicken and cheapen its production. I

The gas or flame in practice I prefer to introduce first high up in thekiln by-injecting it into and throughout the upper layers through a dooror opening a moderate distance below the top of the charge. The currentof fire soon ignites the whole of the upper part of the charge anddrives off by intense heat through the chimney the heavy carbonic-acidgas produced by the decomposition of the large proportion of carbonateof lime in the mirlture; but for the intense heat of the upper stratathis gas would lag in the kiln and badly choke theslow ignition of theordinary burning process. Moreover, the proper clinkeringof the upperstrata is thus assured an effect seldom produced in any other way. Thiscovering of the upper portion of the charge with a largeactively-burning mass of materials induces a strong draft upward throughthe grate at the bottom in such a way that when the fire is afterwardapplied to the bottom of the contents it rapidly rises and widens outthroughout the entire contents. In this way the binder is nearly allburned in situ, and what portion of it volatilizes is burned in theupper incandescent layers, scarcely any escaping as waste vapor. Theslippery softening of the balls or blocks held together by it is so fardiminished that the interstices are not materially closed under thegreat superincu mbent weight of the charge, and the draft therefore butlittle impeded. The entire charge burning at the same time throughout issubject to a much higher heat than if burned in successive stages, andis therefore better and more uniformly brought to the properlyclinkeredpoint.

The lighting of the kiln near the top first, and subsequently at thebottom, brings about the best results; but without departure from myinvention the kiln may be lighted at the bottom simultaneously with or ashort time before its lighting at the top, the latter operation stillacting to produce upon the lower burning and the general burning of thekiln the special effects hereinbefore mentioned namely, the more rapidexpulsion of the carbonic-acid gas of the kiln and the improvement inthe draft of the entire kiln, as well as the more efficient and rapidreduction of the charge; nor am I restricted in my invention to thosecases only where the materials to be reduced or changed by heat areassociated with a combustible binder, although the invention has specialadvantages and is of special value in such cases. I may apply it togreat advantage in the ordinary manufacture wherein a combustible binderis not used, whether the cement to be produced be of a natural or of aPortland character. I have practically ascertained that when my processof injecting one or more streams of flaming gas or sprayinto the bottomof akiln charged in the ordinary way has been employed I have eifected agreat saving in quantity and cost of fuel and a great saving of time inthe burning process, and when I have applied my invention and process insuch a way as to first thoroughly light the upper strata by directingthe flame through them in various directions, and then to light thelower strata at the bottom of the kiln, I have been able to stillfurther reduce the cost of fuel, to improve the cement by burning thebinder more efficiently in situ, and to re duce the time of burning outthe entire kiln to about half the time required to burn it out in theregular way heretofore practiced, thus vastly economizing and improvingthe manufacturing process and product of a cement- Works and nearlydoubling its reducing capacify.

1 Having described my invention and the best way now known to me ofcarrying the same into eifect, what I claim, and desire to secure byLetters Patent is- In the manufacture of cement, the method hereinbeforedescribed of burning or reducing the cement-making materials in a kilnor chamber by subjecting the same to the si multaneous action both ofthe usual solid fuels previously mixed with the cement-making materialsand forming aportion of the charge and of burning jets of gas, fluids,or spray which are auxiliary and ancillary to the solid fuels and areapplied to the upper strata of the charge in the kiln before or at aboutthe time the lower strata of the same charge are lighted, substantiallyas and for the purposes hereinbefore set forth.

JAMES M. \VILLOOX.

\Vitnesses:

R. W. LEsLEY, V. II. GoDwIN.

